feat(rules): spell components + deafened verbal failure and arcane spell failure rolls

- SpellSpec.components (frozenset of V/S/M/F/DF, JSON key accepting the RAW
  string notation "V, S, M/DF" or a token list; slash = alternative; unknown
  token is a data error). Default empty = not encoded yet -> no failure.
- Combatant.armor_spell_failure (0-100 percent, authored on the JSON - the
  model has no equipment) and arcane_caster (divine casters never incur ASF);
  both load directly through load_combatant.
- _cast_spell: after the start-of-casting gates and before delivery, two
  conditional d100 rolls (convention mirrors the concealment roll, <=):
  deafened + V component spoils the spell on <=20 (SRD cast-a-spell.md);
  arcane_caster + S component + armor_spell_failure > 0 fails the spell on
  <= the ASF percent (SRD arcane-spells-and-armor.md). The slot stays spent
  (mirrors the concentration fizzle). No condition -> no roll: the RNG
  stream is bit-identical for every current combat (registry encodes no
  components yet - full encoding is a follow-up task).
- Observation: spell summary gains "components" (sorted tuple), combatant
  snapshot gains "armor_spell_failure"/"arcane_caster"; README documents
  the keys and the two former out-of-scope bullets now describe the modeled
  rule with its data-encoding follow-up.
- Data smoke test: lich arcane_caster true / ASF 0, oni arcane_caster false.
- tests/test_spell_failure.py: 21 tests (parsing, thresholds <=20 / <=ASF,
  divine/no-ASF/no-component never roll, roll order, slot stays spent,
  observation keys). Golden transcripts unchanged.

README.md

@@ -1691,7 +1691,15 @@ Règles modélisées :
     Large… ; l'allonge effective d'une attaque reste `max(allonge naturelle,
     reach_ft de l'arme)`), aware (SRD « Surprise » : agit au round de surprise),
     alignment (SRD « Alignment » : code à deux axes parmi LG/NG/CG/LN/N/CN/LE/NE/CE,
-    défaut "N"),
+    défaut "N"), armor_spell_failure (SRD « Arcane Spells and Armor » :
+    pourcentage 0-100 d'échec d'incantation arcanique dû à l'armure, authored
+    sur le JSON — le modèle n'a pas d'équipement) et arcane_caster (bool :
+    vrai = incanteur arcanse exposé à l'ASF, faux = incanteur divin jamais
+    exposé), armor_spell_failure (int 0-100 — pourcentage d'échec
+    d'incantation arcanique de l'armure, SRD « Arcane Spells and Armor »,
+    authored sur le JSON faute de modèle d'équipement) et arcane_caster
+    (bool — vrai pour un incanteur arcanse exposé à l'ASF, faux pour un
+    incanteur divin),
     dr {amount, bypass} ou None (C1), creature_type (C3),
     bab (E1), initiative_mod (E2) et initiative_total (U2 : total du jet
     d'initiative courant = d20 + mod, 0 si pas encore de clé — invocation
@@ -1716,7 +1724,9 @@ Règles modélisées :
     radius_ft, centered_on_caster} | None (U7a : premier AreaEffect de niveau supérieur du sort,
     gabarit de zone structuré, None si le sort n'a pas de zone), cast_time
     (code de temps d'incantation, « standard » pour un sort inconnu du
-    registre)),
+    registre), components (tuple trié des tokens de composantes V/S/M/F/DF,
+    SRD « Cast a Spell — Spell Components » ; vide = composantes non
+    encodées — aucun échec de composante possible pour ce sort)),
     spell_resistance (int), resistances {type: montant}, immunities
     (tuple triée des types immunisés), sneak_dice (dés de précision disponibles :
     (niveau + 1) // 2 avec « Sneak Attack », sinon 0), engaged_in_melee (bool —
@@ -1844,27 +1854,35 @@ plutôt que bricolées) :
   large ones, may present an obstacle even when helpless. In such cases, each
   square you move through counts as 2 squares » — les cases d'une créature
   inactive ne bloquent pas et ne coûtent pas double).
-- **Échec d'incantation pour un personnage sourd hors périmètre** (SRD
+- **Composantes des sorts et échecs d'incantation associés — moteur en
-  « Conditions — Deafened » : « a 20% chance of spell failure when casting
+  place, encodage des données en cours** (SRD « Cast a Spell — Spell
-  spells with verbal components ») : le moteur ne porte pas la composante
+  Components » : « A spellcaster who has been deafened has a 20% chance to
-  verbale des sorts (`SpellSpec` n'a pas de champ `components` — il
+  spoil any spell he tries to cast if that spell has a verbal component » ;
-  faudrait l'encoder sur les 108 sorts du registre) et ne modélise pas non
+  SRD « Arcane Spells and Armor » : « If you cast an arcane spell with a
-  plus le jet de Perception DD 20 basé sur le son ni l'échec automatique
+  somatic component while wearing armor, you incur a chance of arcane spell
-  associé ; la condition `deafened` reste donc un porteur de modificateurs
+  failure ») : `SpellSpec` porte un champ `components` (liste de tokens
-  (−4 d'initiative) sans la faillibilité d'incantation. Le soin des
+  parmi V/S/M/F/DF, notation RAW acceptée — `"V, S, M/DF"` où la barre
+  oblique sépare les alternatives) et `Combatant` porte
+  `arcane_caster` (vrai pour les incanteurs arcanses — le liche ; faux
+  pour les incanteurs divins — Oni) et `armor_spell_failure` (pourcentage
+  0-100 authored sur le JSON, le modèle n'ayant pas d'équipement — la CA
+  des JSON est une valeur finale). `_cast_spell` joue les deux jets après
+  les gardes de début d'incantation (emplacement déjà dépensé — un échec
+  brûle l'emplacement, comme le fumble de concentration) : d100 ≤ 20 si le
+  lanceur est `deafened` et le sort a la composante V
+  (journalisé `casting failed (deafened)`) ; d100 ≤ l'ASF si le lanceur
+  est arcanse, porte la condition `S` et a un ASF > 0 (journalisé
+  `arcane spell failure`) ; convention `<=` miroir du jet de
+  dissimulation. Chaque jet n'est joué que si sa condition tient : un
+  lanceur non-sourd et dépourvu d'ASF garde un flux RNG bit-identique.
+  Reste hors périmètre (tâche de suivi) : l'encodage des composantes sur
+  les 108 sorts du registre `data/spells/` (aucun sort ne déclare encore
+  de composante, donc aucun échec ne peut partir dans les combats
+  dorés) ; le jet de Perception DD 20 basé sur le son du sourd et son
+  échec automatique associé ne sont pas modélisés. Le soin des
   morts-vivants par les sorts de soin (`cure`) est en revanche modélisé :
   SRD « Cure Light Wounds » — « this spell deals damage to them instead of
   curing their wounds [...] can attempt a Will save to take half damage ».
-- **Échec d'incantation arcanique due à l'armure (ASF) hors périmètre** (SRD
-  « Arcane Spells and Armor » : « Armor restricts the complicated gestures
-  required while casting any spell that has a somatic component. The armor
-  and shield descriptions list the arcane spell failure chance for different
-  armors and shields ») : le moteur ne modélise pas l'équipement — le
-  `Combatant` n'a aucun champ armure/bouclier (la CA des JSON est une valeur
-  finale, voir « Taille et attaques/CA ») et `SpellSpec` n'a aucun champ
-  `components` (même constat que la limite « personnage sourd » ci-dessus) ;
-  la probabilité d'échec d'incantation n'a donc ni source (montant d'ASF de
-  l'armure) ni filtre (sorts à composante somatique) et n'est pas appliquée.
 - **Congé des sorts à durée « (D) » hors périmètre** (SRD « Cast a Spell —
   Dismiss a Spell » : « Dismissing an active spell is a standard action
   that doesn't provoke attacks of opportunity » ; marque « (D) » de la
@@ -1969,7 +1987,9 @@ Limites de sorts (conformance D6-D9, documentées plutôt que bricolées) :
 - `spells.py` — sorts : `SpellSpec` (dataclass avec niveau, école, portée,
   sauvegarde, DC de base, exigence de contact à distance `requires_ranged_touch`
   (rayons), marque `harmless` (SRD « (harmless) » — sauvegarde sautée sur
-  cible consentante), temps d'incantation `cast_time`) et types d'effets
+  cible consentante), temps d'incantation `cast_time`, composantes
+  `components` (frozenset de tokens V/S/M/F/DF, SRD « Cast a Spell — Spell
+  Components »)) et types d'effets
   (`DamageEffect`, `ConditionEffect`,
   `HealEffect`, `BuffEffect`, `AreaEffect` — burst/cône/ligne, S1a,
   `OneShotEffect` — bonus compétence à usage unique sur un jet d'attaque, de

data/monsters/lich.json

@@ -27,6 +27,8 @@
     "will": 11
   },
   "casting_ability": "int",
+  "arcane_caster": true,
+  "armor_spell_failure": 0,
   "spell_slots": {
     "1": 4,
     "2": 4,

data/pcs/oni.json

@@ -26,6 +26,8 @@
   "will": 9
  },
  "casting_ability": "wis",
+ "arcane_caster": false,
+ "armor_spell_failure": 0,
  "spell_slots": {
   "1": 4,
   "2": 3

src/pf1e_simulator/combat.py

@@ -216,6 +216,10 @@ _FIGHT_DEFENSIVELY_AC_BONUS = 2  # PF1e: fighting defensively grants +2 dodge AC
 _FIGHT_DEFENSIVELY_ATTACK_PENALTY = -4  # PF1e: and -4 on attacks / crit confirms
 _SPELL_COMBAT_ATTACK_PENALTY = -2  # PF1e: magus Spell Combat melee attacks at -2
 _TOTAL_CONCEALMENT_PCT = 50  # PF1e: a blinded attacker's targets have total concealment
+# PF1e (SRD Cast a Spell - Components): "A spellcaster who has been deafened
+# has a 20% chance to spoil any spell he tries to cast if that spell has a
+# verbal component" (rules/prpg-core-rulebook/cast-a-spell.md).
+_DEAFENED_VERBAL_FAILURE_PCT = 20
 # PF1e (CRB Damage Reduction): DR does not negate energy damage dealt along
 # with an attack — only these weapon damage types ride the DR path.
 _PHYSICAL_DAMAGE_TYPES = frozenset({"bludgeoning", "piercing", "slashing"})
@@ -1661,6 +1665,8 @@ class CombatEngine:
             "natural_reach_ft": _SIZE_NATURAL_REACH_FT.get(state.combatant.size, 5),
             "aware": state.combatant.aware,
             "alignment": state.combatant.alignment,
+            "armor_spell_failure": state.combatant.armor_spell_failure,
+            "arcane_caster": state.combatant.arcane_caster,
             "creature_type": state.combatant.creature_type,
             "bab": state.combatant.bab,
             "initiative_mod": state.combatant.initiative_mod,
@@ -6536,6 +6542,7 @@ class CombatEngine:
                 "harmless": False,
                 "area": None,
                 "cast_time": "standard",
+                "components": (),
             }
         half_on_save = _spell_half_on_save(spell)
         return {
@@ -6551,6 +6558,7 @@ class CombatEngine:
             "harmless": spell.harmless,
             "area": _spell_area_dict(spell),
             "cast_time": spell.cast_time,
+            "components": tuple(sorted(spell.components)),
         }
 
     def _cast_spell(
@@ -6624,9 +6632,16 @@ class CombatEngine:
             caster.held_charge = None
         # PF1e (CRB, Concentration, B24): grappled/defensive/threatened casts
         # must clear their interruption gate before the spell is delivered.
-        if self._spell_cast_interrupted(
+        # PF1e (SRD Cast a Spell - Components): then the component failure
+        # rolls (deafened + verbal, arcane + somatic + armor), made during
+        # the cast itself - the slot is already spent, mirroring the
+        # concentration-fizzle path. Each d100 is rolled ONLY when its
+        # condition applies, so a non-deafened or unarmored caster keeps a
+        # bit-identical RNG stream.
+        interrupted = self._spell_cast_interrupted(
             caster, used_level, cast_defensively=cast_defensively
-        ):
+        )
+        if interrupted or self._spell_component_failure(caster, spell, spell_name):
             return None
         if spell.cast_time == "one_round":
             # PF1e (SRD "Casting Time"): "A spell that takes 1 round to cast
@@ -6734,6 +6749,49 @@ class CombatEngine:
                 return True
         return self._check_casting_aoo(caster, spell_level)
 
+    def _spell_component_failure(
+        self, caster: CombatantState, spell: SpellSpec, spell_name: str
+    ) -> bool:
+        """Component failure rolls, made during the cast (SRD "Cast a Spell -
+        Spell Components").
+
+        - Deafened + verbal: "A spellcaster who has been deafened has a 20%
+          chance to spoil any spell he tries to cast if that spell has a
+          verbal component" (rules/prpg-core-rulebook/cast-a-spell.md).
+        - Arcane + somatic + armor: "Armor restricts the complicated
+          gestures required while casting any spell that has a somatic
+          component" (rules/prpg-core-rulebook/arcane-spells-and-armor.md) -
+          divine casters (``arcane_caster`` false) never roll.
+
+        Each d100 is rolled ONLY when its condition applies, so a
+        non-deafened, unarmored or divine caster keeps a bit-identical RNG
+        stream. Convention mirrors the concealment roll: failure on
+        d100 <= the percent. True = the spell is spoiled (logged; the slot
+        stays spent), False = the cast survives every applicable roll.
+        """
+        if "V" in spell.components and self._has_condition_named(
+            caster, "deafened"
+        ):
+            pct = self._rng.d100()
+            if pct <= _DEAFENED_VERBAL_FAILURE_PCT:
+                self._log(
+                    f"round {self._current_round} {caster.combatant.id}: "
+                    f"casting failed (deafened): d100({pct}) <= "
+                    f"{_DEAFENED_VERBAL_FAILURE_PCT}% - {spell_name} lost"
+                )
+                return True
+        asf = caster.combatant.armor_spell_failure
+        if "S" in spell.components and caster.combatant.arcane_caster and asf > 0:
+            pct = self._rng.d100()
+            if pct <= asf:
+                self._log(
+                    f"round {self._current_round} {caster.combatant.id}: "
+                    f"arcane spell failure: d100({pct}) <= {asf}% - "
+                    f"{spell_name} lost"
+                )
+                return True
+        return False
+
     def _spell_delivery_blocked(
         self,
         caster: CombatantState,

src/pf1e_simulator/loaders/combatant.py

@@ -239,6 +239,9 @@ def load_combatant(path: Path) -> Combatant:
     ``Combatant`` schema (default ``true``), so it parses directly here.
     The ``alignment`` code (SRD "Alignment") is a plain string of the schema
     (default ``"N"``), so a JSON ``alignment`` key loads directly too.
+    The ``armor_spell_failure`` percent and the ``arcane_caster`` flag
+    (SRD "Arcane Spells and Armor") are plain fields of the schema (defaults
+    ``0`` and ``false``), so their JSON keys load directly as well.
     """
     try:
         raw = path.read_text(encoding="utf-8")

src/pf1e_simulator/models.py

@@ -322,6 +322,16 @@ class Combatant(_FrozenModel):
     metamagic_feats: list[str] = Field(default_factory=list)  # e.g. Empower/Maximize/Extend Spell
     spells: list[str] = Field(default_factory=list)
     spell_resistance: int = 0
+    # PF1e (SRD, Magic - Arcane Spells and Armor): the armor/shield worn
+    # imposes an arcane spell failure chance (percent, 0-100) on arcane
+    # spells with a somatic component. The model has no equipment, so the
+    # chance is authored directly on the combatant JSON.
+    # rules/prpg-core-rulebook/arcane-spells-and-armor.md
+    armor_spell_failure: int = Field(default=0, ge=0, le=100)
+    # True when the combatant's spellcasting is arcane (sorcerer, wizard,
+    # magus...) - only arcane casters incur armor spell failure; divine
+    # casters (cleric, druid...) wear any armor freely.
+    arcane_caster: bool = False
     resistances: dict[str, int] = Field(default_factory=dict)
     immunities: tuple[str, ...] = ()
     # PF1e (SRD "Surprise"): "If some but not all of the combatants are aware

src/pf1e_simulator/spells.py

@@ -462,6 +462,14 @@ class SpellSpec:
     # voluntarily forego a saving throw and willingly accept a spell's
     # result"), so the engine skips the save roll on same-side targets.
     harmless: bool = False
+    # PF1e (SRD, Magic - Cast a Spell - Spell Components): the components a
+    # spell requires, as normalized uppercase tokens among V (verbal),
+    # S (somatic), M (material), F (focus), DF (divine focus)
+    # (rules/prpg-core-rulebook/cast-a-spell.md). Empty = no components
+    # encoded yet (the registry is not fully transcribed), which makes both
+    # component-gated failure rolls (deafened casting, arcane spell failure)
+    # impossible for that spell.
+    components: frozenset[str] = frozenset()
     effects: tuple[SpellEffect, ...] = ()
     description: str = ""
 
@@ -572,6 +580,38 @@ def _is_cast_time(value: str) -> TypeGuard[CastTime]:
     return value in get_args(CastTime)
 
 
+# PF1e spell components (SRD, Magic - Cast a Spell - Spell Components):
+# verbal, somatic, material, focus, divine focus.
+_SPELL_COMPONENTS: frozenset[str] = frozenset({"V", "S", "M", "F", "DF"})
+
+
+def _parse_components(value: Json) -> frozenset[str]:
+    """Spell components from a RAW string ("V, S, M/DF") or a token list.
+
+    The SRD stat-block notation separates components with commas and
+    alternatives (material OR divine focus) with a slash; both delimiters
+    split into tokens, normalized to uppercase and validated against
+    {V, S, M, F, DF}. An unknown token is a data error.
+    """
+    if isinstance(value, str):
+        raw_tokens = value.replace("/", ",").split(",")
+    else:
+        raw_tokens = [_as_str(item) for item in _as_list(value)]
+    tokens: set[str] = set()
+    for raw in raw_tokens:
+        token = raw.strip().upper()
+        if not token:
+            continue
+        if token not in _SPELL_COMPONENTS:
+            msg = (
+                f"unknown spell component: {raw!r} "
+                f"(expected one of {sorted(_SPELL_COMPONENTS)})"
+            )
+            raise ValueError(msg)
+        tokens.add(token)
+    return frozenset(tokens)
+
+
 # RAW phrasings accepted by the JSON loader, mapped onto the budget codes.
 _CAST_TIME_ALIASES: dict[str, CastTime] = {
     "1 round": "one_round",
@@ -983,6 +1023,10 @@ def load_spell(path: str | Path) -> SpellSpec:
         msg = f"unknown save type: {save_raw!r}"
         raise ValueError(msg)
     cast_time = _parse_cast_time(_as_str(data.get("cast_time", "standard")))
+    components_raw = data.get("components")
+    components = (
+        frozenset[str]() if components_raw is None else _parse_components(components_raw)
+    )
     return SpellSpec(
         name=_as_str(data["name"]),
         level=_as_int(data["level"]),
@@ -994,6 +1038,7 @@ def load_spell(path: str | Path) -> SpellSpec:
         cast_time=cast_time,
         spell_resistance=bool(data.get("spell_resistance", True)),
         harmless=bool(data.get("harmless", False)),
+        components=components,
         effects=effects,
         description=_as_str(data.get("description", "")),
     )

tests/test_observation_enriched.py

@@ -534,6 +534,7 @@ def test_observation_enriched_spells_unknown_graceful() -> None:
             "harmless": False,
             "area": None,
             "cast_time": "standard",
+            "components": (),
         },
     )
 

tests/test_spell_area_snapshot.py

@@ -143,6 +143,7 @@ def test_area_snapshot_existing_keys_unchanged() -> None:
     assert s["save_negates"] is False
     assert s["harmless"] is False
     assert s["cast_time"] == "standard"
+    assert s["components"] == ()
     assert set(s.keys()) == {
         "name",
         "level",
@@ -156,6 +157,7 @@ def test_area_snapshot_existing_keys_unchanged() -> None:
         "harmless",
         "area",
         "cast_time",
+        "components",
     }
 
 

tests/test_spell_failure.py

@@ -0,0 +1,339 @@
+"""Spell components and the component-gated casting failures.
+
+SRD sources:
+- rules/prpg-core-rulebook/cast-a-spell.md (components V/S/M/F/DF):
+  "A spellcaster who has been deafened has a 20% chance to spoil any spell
+  he tries to cast if that spell has a verbal component."
+- rules/prpg-core-rulebook/arcane-spells-and-armor.md:
+  "Armor restricts the complicated gestures required while casting any
+  spell that has a somatic component." - arcane casters only.
+
+The rolls are conditional: a non-deafened caster never rolls the deafened
+d100, a divine caster (arcane_caster false) or asf=0 never rolls the ASF
+d100, and a spell without the component never triggers its roll - so the
+RNG stream stays bit-identical for everyone else. Failure burns the slot
+(mirrors the concentration-fizzle path). The roll convention mirrors the
+concealment d100: failure on d100 <= the percent.
+"""
+
+from __future__ import annotations
+
+import json
+from pathlib import Path
+from typing import TYPE_CHECKING
+
+import pytest
+
+from pf1e_simulator.combat import CombatantState, CombatEngine
+from pf1e_simulator.conditions import DEAFENED
+from pf1e_simulator.loaders.combatant import CombatantLoadError, load_combatant
+from pf1e_simulator.rng import ScriptedRng
+from pf1e_simulator.spells import (
+    ConditionEffect,
+    SpellSpec,
+    load_spell,
+    load_spell_registry,
+)
+from tests.test_observation_enriched import make_combatant, make_grid, make_state
+
+if TYPE_CHECKING:
+    from pf1e_simulator.models import Combatant
+
+DATA_DIR = Path(__file__).resolve().parent.parent / "data"
+
+
+def _zap(name: str, components: frozenset[str]) -> SpellSpec:
+    """A save-less condition spell: applying it consumes no dice, so the
+    test queues pin exactly the failure rolls."""
+    return SpellSpec(
+        name=name,
+        level=1,
+        school="transmutation",
+        range="close",
+        components=components,
+        effects=(ConditionEffect(condition_name="shaken", duration_rounds=1),),
+    )
+
+
+def _caster(
+    spell: SpellSpec,
+    *,
+    arcane_caster: bool = False,
+    armor_spell_failure: int = 0,
+) -> Combatant:
+    base = make_combatant("caster", spells=[spell.name], spell_slots={1: 1})
+    return base.model_copy(
+        update={
+            "arcane_caster": arcane_caster,
+            "armor_spell_failure": armor_spell_failure,
+        }
+    )
+
+
+def _cast(
+    caster: Combatant,
+    spell: SpellSpec,
+    rolls: list[int],
+    *,
+    deafened: bool = False,
+) -> tuple[CombatEngine, CombatantState, CombatantState, ScriptedRng]:
+    grid = make_grid()
+    c = make_state(caster, "players", (0, 0))
+    t = make_state(make_combatant("foe"), "monsters", (2, 0))
+    if deafened:
+        c.conditions.append(DEAFENED)
+    rng = ScriptedRng(rolls)
+    engine = CombatEngine(rng, grid, [c, t], spell_registry={spell.name: spell})
+    engine._cast_spell(c, t, spell.name)
+    return engine, c, t, rng
+
+
+def _shaken(state: CombatantState) -> bool:
+    return any(ac.condition.name == "shaken" for ac in state.active_conditions)
+
+
+def _transcript(engine: CombatEngine) -> str:
+    return "\n".join(engine._transcript)
+
+
+def _goblin_payload() -> dict[str, object]:
+    path = DATA_DIR / "monsters" / "goblin.json"
+    data: dict[str, object] = json.loads(path.read_text(encoding="utf-8"))
+    return data
+
+
+# ---------------------------------------------------------------------------
+# loader: the components key
+# ---------------------------------------------------------------------------
+
+
+def _write_spell(tmp_path: Path, payload: dict[str, object]) -> SpellSpec:
+    path = tmp_path / "spell.json"
+    path.write_text(json.dumps(payload), encoding="utf-8")
+    return load_spell(path)
+
+
+def test_components_string_srd_notation(tmp_path: Path) -> None:
+    """Given: the RAW stat-block notation "V, S, M/DF"
+    When: load_spell parses it
+    Then: the tokens normalize to {V, S, M, DF} (slash = alternative)."""
+    spell = _write_spell(
+        tmp_path,
+        {"name": "X", "level": 1, "school": "x", "components": "V, S, M/DF"},
+    )
+    assert spell.components == frozenset({"V", "S", "M", "DF"})
+
+
+def test_components_list_of_tokens(tmp_path: Path) -> None:
+    spell = _write_spell(
+        tmp_path,
+        {"name": "X", "level": 1, "school": "x", "components": ["v", "S"]},
+    )
+    assert spell.components == frozenset({"V", "S"})
+
+
+def test_components_default_empty(tmp_path: Path) -> None:
+    spell = _write_spell(tmp_path, {"name": "X", "level": 1, "school": "x"})
+    assert spell.components == frozenset()
+
+
+def test_components_unknown_token_rejected(tmp_path: Path) -> None:
+    with pytest.raises(ValueError, match="unknown spell component"):
+        _write_spell(
+            tmp_path,
+            {"name": "X", "level": 1, "school": "x", "components": "V, Q"},
+        )
+
+
+def test_components_bad_type_rejected(tmp_path: Path) -> None:
+    with pytest.raises(ValueError, match="expected list"):
+        _write_spell(
+            tmp_path,
+            {"name": "X", "level": 1, "school": "x", "components": 3},
+        )
+
+
+def test_combatant_caster_fields_load_from_json(tmp_path: Path) -> None:
+    """Given: a combatant JSON with armor_spell_failure and arcane_caster
+    When: load_combatant parses it
+    Then: both fields land on the model."""
+    payload = _goblin_payload()
+    payload["armor_spell_failure"] = 25
+    payload["arcane_caster"] = True
+    path = tmp_path / "armored.json"
+    path.write_text(json.dumps(payload), encoding="utf-8")
+    loaded = load_combatant(path)
+    assert loaded.armor_spell_failure == 25
+    assert loaded.arcane_caster is True
+
+
+def test_armor_spell_failure_out_of_bounds_rejected(tmp_path: Path) -> None:
+    payload = _goblin_payload()
+    payload["armor_spell_failure"] = 101
+    path = tmp_path / "bad.json"
+    path.write_text(json.dumps(payload), encoding="utf-8")
+    with pytest.raises(CombatantLoadError, match="armor_spell_failure"):
+        load_combatant(path)
+
+
+# ---------------------------------------------------------------------------
+# deafened + verbal component: 20% spoil chance
+# ---------------------------------------------------------------------------
+
+
+def test_deafened_verbal_fails_at_threshold() -> None:
+    """d100 = 20 <= 20: the spell is spoiled, the slot stays spent, no
+    effect lands."""
+    spell = _zap("Buzz", frozenset({"V"}))
+    caster = _caster(spell)
+    engine, c, t, rng = _cast(caster, spell, [20], deafened=True)
+    assert _shaken(t) is False
+    assert c.spell_slots_left[1] == 0
+    assert "casting failed (deafened)" in _transcript(engine)
+    assert len(rng._queue) == 0
+
+
+def test_deafened_verbal_succeeds_above_threshold() -> None:
+    spell = _zap("Buzz", frozenset({"V"}))
+    caster = _caster(spell)
+    engine, c, t, rng = _cast(caster, spell, [21], deafened=True)
+    assert _shaken(t) is True
+    assert c.spell_slots_left[1] == 0
+    assert "casting failed (deafened)" not in _transcript(engine)
+    assert len(rng._queue) == 0
+
+
+def test_deafened_without_verbal_never_rolls() -> None:
+    """A spell with no V component: the deafened caster casts it with no
+    roll - the RNG stream is untouched."""
+    spell = _zap("Quiet", frozenset({"S"}))
+    caster = _caster(spell)
+    _engine, _c, t, rng = _cast(caster, spell, [], deafened=True)
+    assert _shaken(t) is True
+    assert len(rng._queue) == 0
+
+
+def test_not_deafened_with_verbal_never_rolls() -> None:
+    spell = _zap("Buzz", frozenset({"V"}))
+    caster = _caster(spell)
+    _engine, _c, t, rng = _cast(caster, spell, [], deafened=False)
+    assert _shaken(t) is True
+    assert len(rng._queue) == 0
+
+
+# ---------------------------------------------------------------------------
+# arcane + somatic + armor: ASF percent
+# ---------------------------------------------------------------------------
+
+
+def test_arcane_somatic_fails_at_asf_threshold() -> None:
+    """d100 = 25 <= ASF 25: the spell is spoiled, slot spent, no effect."""
+    spell = _zap("Gesticulate", frozenset({"S"}))
+    caster = _caster(spell, arcane_caster=True, armor_spell_failure=25)
+    engine, c, t, rng = _cast(caster, spell, [25])
+    assert _shaken(t) is False
+    assert c.spell_slots_left[1] == 0
+    assert "arcane spell failure" in _transcript(engine)
+    assert len(rng._queue) == 0
+
+
+def test_arcane_somatic_succeeds_above_asf() -> None:
+    spell = _zap("Gesticulate", frozenset({"S"}))
+    caster = _caster(spell, arcane_caster=True, armor_spell_failure=25)
+    engine, _c, t, rng = _cast(caster, spell, [26])
+    assert _shaken(t) is True
+    assert "arcane spell failure" not in _transcript(engine)
+    assert len(rng._queue) == 0
+
+
+def test_divine_caster_never_rolls_asf() -> None:
+    """arcane_caster false with armor_spell_failure 35: no roll, ever."""
+    spell = _zap("Gesticulate", frozenset({"S"}))
+    caster = _caster(spell, arcane_caster=False, armor_spell_failure=35)
+    _engine, _c, t, rng = _cast(caster, spell, [])
+    assert _shaken(t) is True
+    assert len(rng._queue) == 0
+
+
+def test_zero_asf_never_rolls() -> None:
+    spell = _zap("Gesticulate", frozenset({"S"}))
+    caster = _caster(spell, arcane_caster=True, armor_spell_failure=0)
+    _engine, _c, t, rng = _cast(caster, spell, [])
+    assert _shaken(t) is True
+    assert len(rng._queue) == 0
+
+
+def test_somatic_free_spell_never_rolls_asf() -> None:
+    """An arcane caster in heavy armor casts a V-only spell with no ASF
+    roll (SRD: "If a spell doesn't have a somatic component, an arcane
+    spellcaster can cast it with no arcane spell failure chance")."""
+    spell = _zap("Chant", frozenset({"V"}))
+    caster = _caster(spell, arcane_caster=True, armor_spell_failure=45)
+    _engine, _c, t, rng = _cast(caster, spell, [])
+    assert _shaken(t) is True
+    assert len(rng._queue) == 0
+
+
+def test_deafened_arcane_both_rolls_in_order() -> None:
+    """V+S spell, deafened arcane caster in armor: the deafened d100 is
+    rolled first and passes, then the ASF d100 spoils the spell."""
+    spell = _zap("Incant", frozenset({"V", "S"}))
+    caster = _caster(spell, arcane_caster=True, armor_spell_failure=30)
+    engine, c, t, rng = _cast(caster, spell, [50, 10], deafened=True)
+    assert _shaken(t) is False
+    assert c.spell_slots_left[1] == 0
+    transcript = _transcript(engine)
+    assert "arcane spell failure: d100(10) <= 30%" in transcript
+    assert "casting failed (deafened)" not in transcript
+    assert len(rng._queue) == 0
+
+
+def test_deafened_failure_short_circuits_asf() -> None:
+    """The deafened roll spoils the spell before the ASF die is touched:
+    exactly one d100 consumed."""
+    spell = _zap("Incant", frozenset({"V", "S"}))
+    caster = _caster(spell, arcane_caster=True, armor_spell_failure=30)
+    _engine, _c, t, rng = _cast(caster, spell, [5], deafened=True)
+    assert _shaken(t) is False
+    assert len(rng._queue) == 0
+
+
+# ---------------------------------------------------------------------------
+# observation: the new keys
+# ---------------------------------------------------------------------------
+
+
+def test_observation_exposes_components_and_caster_fields() -> None:
+    spell = _zap("Incant", frozenset({"V", "S"}))
+    caster = _caster(spell, arcane_caster=True, armor_spell_failure=15)
+    c = make_state(caster, "players", (0, 0))
+    t = make_state(make_combatant("foe"), "monsters", (2, 0))
+    engine = CombatEngine(
+        ScriptedRng([]), make_grid(), [c, t], spell_registry={spell.name: spell}
+    )
+    obs = engine._build_observation(c).to_dict()
+    hero = next(x for x in obs["combatants"] if x["id"] == "caster")
+    assert hero["arcane_caster"] is True
+    assert hero["armor_spell_failure"] == 15
+    (snap,) = hero["spells"]
+    assert snap["components"] == ("S", "V")
+    json.dumps(obs)
+
+
+def test_lich_is_arcane_oni_is_not() -> None:
+    """Smoke test on the shipped data: the lich casts arcane spells with
+    no armor (ASF 0); Oni is a divine caster and never incurs ASF."""
+    lich = load_combatant(DATA_DIR / "monsters" / "lich.json")
+    oni = load_combatant(DATA_DIR / "pcs" / "oni.json")
+    assert lich.arcane_caster is True
+    assert lich.armor_spell_failure == 0
+    assert oni.arcane_caster is False
+    assert oni.armor_spell_failure == 0
+
+
+def test_registry_spells_have_no_components_yet() -> None:
+    """The full component encoding is a follow-up: no shipped spell
+    declares components, so no golden combat can roll a failure."""
+    registry = load_spell_registry(DATA_DIR / "spells")
+    assert registry
+    assert all(spell.components == frozenset() for spell in registry.values())